The present invention relates generally to brush chippers, and more particularly to a novel arrangement for coupling a brush chipper's motor output shaft to the feed wheel shaft of the same machine.
Generally, brush chippers are comprised of a feed system and a cutting system. The feed system includes an opening into which brush is inserted. Feed wheels within the opening rotate to pull the brush into the cutting system. The cutting system includes a mechanism for cutting the brush into small chips which are then discharged.
The feed wheels are often formed as opposed drums (or cylinders) providing a nip into which the brush is received. Typically, each of the feed wheel drums has a drive shaft driven by a respective hydraulic motor. In the past, a variety of coupling arrangements have been provided to connect the motor output shaft to the drive shaft of the feed wheel drum. These prior arrangements, however, have each had significant drawbacks in either the operation or serviceability of the brush chipper.
For example, those in the art have conventionally used couplers employing two pins extending through the coupler and into the respective shafts being joined. That is, the coupler and each shaft would have radial bores (one on each end of the coupler and one in each shaft) in which respective pins were inserted. An interference fit between the pins and bore walls would create a connection between the shafts via the coupler. Unfortunately, upon failure of the motor, the coupler, or either of the shafts, it was difficult to separate the shafts from the coupler. Often, the only way to remove the coupler was to destroy it. As a result, the coupler and connected parts were often damaged beyond repair.
Another prior art technique of connecting the feed wheel drive shaft and motor output shaft was to use a chain coupler. This arrangement, while easily removable, sometimes suffers from a strength deficiency. That is, the forces transmitted from the motor output shaft to the feed wheel shaft can be too high to be transferred reliably through a chain coupler. Yet another technique, connecting straight motor output and feed wheel shafts with a coupler having keyways, is often unsatisfactory because the keys may not be sufficiently strong by themselves to prevent shearing.